2700: To avoid apocalypse by global warming, a powerful nation (probably America) stops the Gulf Stream. This puts Europe into an ice age, and averts the impeding disaster. However, Europe was not ready, and when World War III comes (2900-3000) they have already been reduced to a hunter-gatherer society (albeit one with higher technology weapons than your average pre- or post- Rome tribe).
After the war, a clever person named Joal comes up with a way of making ice very sharp, and so usable for spears/knifes/axes. Meanwhile, traders have noticed that getting good flint/steel/iron/other materials for weapons is rather hard on the frozen continent, that they might pay quite a lot for a good knife/spear/etc. .
So how rich should Joal expect to get, as ice is the only readily available material, and the traders are overcharging?
EDIT: After the War, all tech is unusable. See this post for some reasons.